Under the great background of globalization today,communications between China and America are more frequent,it becomes significant for us to gain a deeper understanding of American presidents’ speech.Obama serves as an example for us to study in this aspect.Until now,most people have been studying his speech mainly through either Chinese translations of his speeches or interpretations by the media,conducted through perspectives which are by no means rhetorically informed.Considering the fact that what we are dealing with is political speech,it is high time that the rhetorical perspective be introduced into the process of interpreting Obama’s political communication in its original context.Such a perspective will help us obtain a better approach of interpreting his speech.This thesis has widely selected the typical political speeches of president Obama in his Election Campaign process,and analyzed three main rhetorical methods in political speech: simile,metaphor and metonymy.Figure of speech is an expression that departs from the accepted literal sense or from the normal order of words,or in which an emphasis is produced by patterns of sound.It is an especially important resource of poetry;it is also constantly present in all other kinds of speech and writing.The figure of speech is commonly used in political speech.In this part of the thesis the author will analyze three main types of figures in Obama’s speech: Simile,metonymy and Metaphor.